Pendulum operated safety switch



March 23, 1965 A. E. cHEsNu'r PENDULUM OPERATED SAFETY SWITCH Filed March 20. 1961 IN VEN TOR. Amos f.. C//feis/va A Tranen/Ens.

United States Patent O 3,175,059 EENDULUM @PERATED SAFETY SWlTIl-I Amos E. Chesnut, Columbus, Ind., assigner to Arvin Industries, lne., Columbus, Ind., a corporation of [Indiana Filed Mar. 20, 1961, Ser. No. 96,940 11 Claims. (Cl. 20G-61.52)

This invention relates to an electrical switch, and more particularly to a safety switch for an electric circuit.

Safety-type electrical switches having pendulum con- -trols for controlling the operation of the switch contact elements are known in the art. Many such switches employ control members which are swingable in only a single fixed plane for automatically controlling the opening and closing of the switch contacts, see for example Stec Patent No. 2,780,688. Other types of safety switches employ pendulum type control members which are swingable in any plane for opening the switch contacts. The safety switches of this latter type, however, require their control members to be manually reset after they have opened the switch contacts, see for example Maught Patent No. 2,176,770, Salmond Patent No. 2,130,706, and DeWilde Patent No. 1,901,554. Such a requirement of manually resetting a switch is a bothersome task and, if the switch is mounted in a ditlicult position of access within an electrical device, it renders the use of such a switch completely impractical.

It is thus the general object of my invention to provide a safety-type elerctical switch which will overcome the disadvantages discussed above. More specically, it is an object of my invention to provide an electrical switch which will be actuated by rela-tive movement of its control member in any plane, and which will be automatically reset after such actuation. lt is a further object of my invention to provide an electrical switch which can be simply and inexpensively manufactured from a relatively small number of parts, and which may be of a compact size.

In accordance with one form of my invention, I provide a switch comprising a pair of leaf arms electrically insulated from each other adjacent one of their ends and `having a pair of contacts adjacent their opposite ends which normally abut each other to thus close the switch and permit an electric current to iiow therethrough. An actutaing member of an insualting material is movably carried on one of said arms and is provided with means projecting outwardly from the switch, whereby movement of said means in any direction with respect to the switch will move said actuating member into a position to force the leaf arm contacts apart to open the switch.

Other objects and features of my invention will become more apparent from the more detailed description which follows and from the accompanying drawings, in which:

FIG. 1 is a perspective view of a portable electric heater having a safety switch embodying my invention mounted therein;

FlG. 2 is a side elevation of an electrical switch embodying my invention;

FIG. 3 is a side elevation of the switch shown in FIG. 2, but showing said switch in a switch-open position;

FIG. 4 is a side elevation of another embodiment of my invention;

3,l75,l59 Patented Mar. 23, 1965 ICC FIG. 5 is a side elevation of the switch shown in FIG. 4, but showing said switch in a switch-open position; and

FIG. 6 is an enlarged isometric view of the switch actuating plug shown in FIG. 2.

My invention comprises a safety-type electrical switch adapted to be connected into an electric circuit for an electrical device tfor opening said circuit when said device is tilted or moved into a position which would render its continued operation unsafe. A typical example of such an ele-tcrical device is a portable radiant electric heater. If such a heater falls over, or is otherwise tilted in such a manner to dispose its heat-emitting face in a position to radiate heat directly onto an object, it may cause such an object to ignite and burn if the electric circuit supplying current to the heater is not opened.

A portable electric heater of this general type is shown in FIG. 1, and comprises a heater housing lil having a heat-emitting face 12. My switch is adapted to be mounted in such a heater for opening the electric circuit supplying energy to the heater in the event that the heatemitting face. 12 is disposed in a position which would render the continued operation of the heater unsafe.

In the embodiment of my invention illustrated in FIG. 2, I provide a switch comprising spaced leaf arms 14 and 16 adapted to be connected at one of their ends to lead wir..s 17 and 1S. Conveniently, the arms 11i and 16 are electrically insulated from one another at one of their ends by insulating layers 2@ through which a mounting stud 22 extends for connecting the arms to a mounting bracket 24. Contact points 25 and 25 are mounted on the leaf arms 14 and 16, respectively, adjacent their opposite end, and are normally disposed in a switch-closed position in which they are in contact with each other to form a closed circuit between the lead wires 17 and 13. F or reasons that will become more apparent hereinafter, the leaf arm 1d is relatively rigid, and the leaf arm 14 is relatively resilient to bias it into a position to dispose the contacts Z5 and 26 into a switch-closed position.

To control the opening of the contacts 25 and 26, an opening 27 is formed in the leaf arm 16 in which a switch actauting plug 23 formed from an insulating material is movably carried. As shown in FIG, 6, the plug 2S comprises an expanded circular head 3@ having a diameter larger than the opening 27 and adapted to be interposed between the leaf arms 1d and 16. The head 30 is integrally connecte-d to an axially extending shank 32. projecting through the opening 27 in the arm 16, said shank having a substantially smaller diameter than the diameter of the opening 27 to permit the plug to be tilted in any direction with respect to the axis of said opening, and to be movable axially of said opening. The plug 23 has an actuating extension conveniently in the form of a rod 34 connected to the plug and carried within an elongated spring 35 projecting outwardly from the end of said rod to constitute a flexible extension thereof. Conveniently, the end of the spring 35 opposite the plug 2S is received in an end cap 36.

When this embodiment of my invention is mounted in a portable electric heater as shown in FIG. 1, the rod 34 and spring 35 project outwardly from the heat-emitting face 12. Thus, as shown in FIG. 3, if the heater should tip or fall over on its heat-emitting face 12, the rod 3d and spring 35 will move the plug 28 into a position to cause the head 3l? of the plug to bear against the relatively rigid leaf arm 16 and cam the arm 1a into a position to dispose the contacts and 26 in spaced relation to each other and open the switch. Likewise, should any object, for example a piece of cloth, be dropped over the heater face 12, the exible spring will bend, with its movement being transmitted to the rod 34 to also cause the plug 28 to cam the arm 14 into a position to open the contacts 25 and 26. It will also be apparent that axial movement of the plug ZS into engagement with the arm 14 will also cause said contacts to open. When any switch-opening force applied to the plug 28 is removed, the plug will be returned to its switch-closed position as shown in FIG. 2 by the inherent resiliency of the leaf arm 14.

In order to prevent the plug head 3G from camming the arm 14 into a position in which said arm is permanently distorted, a stop 37, conveniently in the form of a snap ring mounted in an annular recess formed in the plug shank 32, is employed to abut the face of the arm 16 and limit the switch-opening movements of said plug.

The embodiment of my invention illustrated in FIG. 4 is adapted to be mounted in an upright position, and will open an electric circuit when it is tilted in any direction from that upright position. The embodiment shown in FIG. 4 comprises a resilient leaf arm 14 and Va relatively rigid leaf arm 16 connected to lead wires 17 and 18', respectively. The two arms are electrically insulated from each other as by insulating layers 24) through which a mounting stud 22 extends for mounting the arms on a switch support 24. Adjacent one of their ends, the arms 14 and 16 are provided with contacts 25 and 26 normally retained in engagement with each other by the inherent resiliency of the arm 14 to thus close the switch between the lead wires 17' and 18.

To open the contacts 25 and 26 upon tilting of the switch, a plug 2S of insulating material is movably mounted on the arm 16 with its shank 32 extending through an opening 27 in said arm and its expanded head 30 carried between the arms 14 and 16. The shank 32 is connected to a weight 38 by an elongated rod 34. As shown in FIG. 5, the weight 3S will retain the plug head 39 in a relatively horizontal plane when the switch is tilted, so that the head 30 will cam against the resilient leaf arm 14; to move the arm with respect to the arm 16 and dispose the contacts Z5 and 26' out of engagement with each other to open the switch. Such a relative movement between the switch and weight 38 will occur when the device in which the switch is mounted is tilted in any direction with respect to the axis of the rod 34. To limit the camming action of the plug 28', the shank 32 of said plug is also provided with a stop 37' engageable with the arm 16 to thus prevent the arm 14' from being bent into a position to cause its permanent distortion.

I claim as my invention:

l. In an electrical switch, a pair of elongated leaf arms having contacts adjacent one of their ends engageable with each other for electrically connecting said arms to close said switch, an actuating member formed of insulating material and movably carried in an opening formed in one of said pair of arms, said member having an expanded head interposed between said arms and bearing against said other of said pair of arms upon movement of said member with respect to said arms to move said pair of arms away from each other and dispose Itheir contacts in spaced relation to each other to open the switch, and elongated means projecting outwardly from said head for moving the same relative to said arms to open the switch.

2. In an electrical switch, a pair of elongated leaf arms insulated from each other toward one of their ends and having contacts adjacent their opposite ends engageable with each other for electrically connecting said arms to close the switch, a plug of insulating material movably carried in one of said pair of arms and having a generally circular head interposed between said arms and d bearing against the other of said pair of arms upon movement of the plug relative to the arms to move said pair of arms away from each other to open their contacts, and means projecting axially of said head for moving the same relative to said arms to open the switch.

3. In an electrical switch, a pair of elongated leaf arms insulated from each other toward one of their ends and having contacts adjacent their opposite ends engageable with each other for electrically connecting said arms to close the switch, one of said pair of arms being relatively rigid and the other of said pair of arms being relatively resilient to urge said contacts into a switchclosed position, a plug of insulating material movably carried in an opening formed in said rigid arm and having a circular head interposed between the two arms, said head having a diameter larger than the diameter of said opening, and means projecting axially of said head for moving the same into engagement with said resilient arm to move it away from said rigid arm to move said contacts into a switch-open position.

4. The invention as set forth in claim 3 with the addition that an abutment is provided on said means for engagement with said rigid arm to limit the movement imparted to said resilient arm by said plug.

5. In an electrical switch, a pair of elongated leaf arms insulated from cach other toward one of their ends and having contacts adjacent their opposite ends engageable with each other for electrically connecting said arms to close the switch, one of said pair of arms being relatively rigid and the other of said pair of arms being relatively resilient to urge said contacts into a switch-closed position, a plug of insulating material having an expanded head interposed between said arms and a shank movably carried in yan opening formed in said rigid leaf arm, and a rod projecting axially of said shank for moving said plug in said opening to cause said head to bear against said resilient arm to move it away from said rigid arm for moving contacts into a switch-open position.

6. The invention as set forth in claim 5 with the addition that a stop is mounted on Isaid shank to limit the movement of the plug in said opening.

7. The invention as set forth in claim 5 with the addition that a rod is carried within a flexible member extending outwardly beyond the end of said rod.

8. In an electrical switch, a pair of elongated leaf arms insulated from each other toward one of their ends and having contacts adjacent their opposite ends engageable with each other for electrically connecting said arms to close the switch, one of said pair of arms being relatively rigid and the other of said pair of arms being rela-tively resilient to urge said contacts into a switchclosed position, a plug of insulating material having an expanded head interposed between said arms and a shank movably carried in an opening formed in said rigid leaf arm, and a weighted member extending axial-ly of said shaft to urge said plug to remain in a susbtantially fixed position and thus cause said head to bear against said resilient arm to move it away from said rigid arm for moving said contacts into a switch-open position upon movement of the switch relative to the axis of said shank.

9. The invention as set forth in claim 8 with the addition that :a stop is mounted on said shank to limit the movement of the plug in said opening.

10. The invention as set forth in claim 8 in which said weighted member comprises an elongated rod connected to said shank, and a weight mounted on said rod.

l1. In an electrical switch, a pair of elongated leaf arms having contacts adjacent one of their ends engageable with each other for electrically connecting said arms to close said switch, an actuating member formed of insulating material movably supported on one of said pair of arms on an axis transverse thereto and in an opening `formed therein, said member having an expanded head interposed between said arms and bearing against said other of said pair of arms upon movement of said member with respect to said arms to move said pair of arms away from each other and disposed their contacts in spaced relation to each other to open the switch, and elongated means projecting outwardly from said head for moving the same axially and tiltably relative to said arms to open the switch.

References Cited in the file of this patent UNITED STATES PATENTS Re. 20,570 Bushway Dec. 7, 1937 1,185,371 Cook May 30, 1916 1,385,588 Sherman et al July 26, 1921 

